Conventionally, for a computer system having a host processor powered by one switchable power supply, and one or more peripheral devices powered by a second alto switchable power supply, the order in which each of the host and peripheral device is powered on may affect the start or boot up procedure. More particularly, if the host is powered on before the peripheral devices, such peripheral devices may either not show up in the configuration, or show up but be identified as non-responding or the like inactive state.
This situation is particularly an issue in host computer systems which serve as database or information servers, and which typically have a host computer and one or more racks or shelves of rotating disk drive storage devices for storing the information. Customarily, each of the host computer processor rack and disc drive racks are powered by separate switchable power supplies. Unfortunately, the order and timing of the power up and power-down of the several racks effects the start-up or boot routine at system initialization, and may cause an error condition on shut-down or power-off.
These conditions have been tolerated in the past by (I) indoctrinating personnel as to the proper power-up and power-down sequence for the host computer and attached devices, (ii) by providing a master power-on switch for all of the equipment, or (iii) by correcting corrupted or erroneous device or system configuration files after the problem has occurred. Unfortunately, neither of the first two options has been entirely successful so that corruption still occurs, and when such corruption occurs, correction typically requires the intervention of a skilled computer administrator.
The problem is particularly acute relative to RAID disc drives on a server being marked logically off-line, some times referred to as simply off-line or "Dead".